Electric switch



A. ROSSMAN March 16, 1943.

ELECTRIC SWITCH Filed Jan. 21, 1938 9 $h'eets-Shet 1 Y F/g. 4

MENTOR Allen M Ross an ATTORNEY.

March 16, 1943. A. M. ROSS MAN 2,313,771

ELECTRIC SWITCH Filed Jan. 21, 1958 9 Sheets-Sheet 2 wn E. NW 3 Unm ,INVENTOR.

. A/len M. Ross/wan ATTORNEY.

March 16, 1943. A. M. ROSSNYIAN ,3

ELECTRIC SWITCH Filed Jan 21,1938 I 9 Sheets Sheeb 3 INVENTOR. Allen M. Eossman March 16, 1943; A. M. RQJSSMAN 2,313,771

ELECTRIC S'WITCH Filed Jan. 21, 1938 9 Sheets-Shet 4 1N VENTOR.

, 1 A/len Eo mcm W ATTORNEY.

March 16, 1943. A, M. ROSQMAN 2,313,171

ELECTRIC SWITCH Filed Jan. 21, 1958 9 shets-sneet s .205 F7 55 F/glfi H957 59.58 5940 INVENTOR.

. Arromxg.

Patented Mar. 16, 11943 UNITED STATES PATENT OFFICE 2,313,771 Emerald swrron Allen M. Rossman,,Wilmette, I'll. Application January 21, 1938, Serial No. 186,177

22 Claims.

This invention relates to electric switchesin general and, more particularly,-to switches of high current carrying capacity. In its more particular aspects the present invention is primarily concerned with the construction of the switch blade or movable current carrying and contact making part of the switch.

In switches of high current carrying capacity it is important that the engagement between the blade and the contact stud be under considerable pressure. Switches have been constructed wherein the engagement is along a number of lines or points, as distinguished from surface engagement, attempts being made to maintain the lines of contact or engagement at the requisite pressure. It is one of the objects of the present invention to provide a switch of the above type wherein the pressure of engagement will be along a number of lines'or points, with a certainty that the pressure or lossof pressure on any line or point will not substantially affect the pressure along an adjacent or other line or point of engagement.

It is a further object of the present invention to provide a switch the blade of which may be fabricated in a simple manner without requiring special tools or dies and requiring no machining or substantially no machining, and which will nevertheless assure a proper pressure engagement between the blade. and the switch stud or studs along a predetermined number of lines or points; In the preferred embodiment of this invention the blade is in the form of a plurality of wires clamped or otherwise secured together in such a manner that the natural resilg iency of the wires may be relied upon to exert the necessary pressure against the contact stud or studs. Great strength and a high degree of resiliency may be obtained by using wires each of which comprises a copper jacket and a core of steel, bronze, or other high strengthelastic material. In those structures wherein a nonmagnetic core must be used I may use bronze, non-magnetic steel, or the like. The copper jacket may be physically united with the core, or i the wire may be formed by inserting a rod into a copper tube and then bending the two together to the required shape. By this arrangement the proportions of copper to core may be of any desired ratio. After the composite wire has been bent to the desired shape, the ends of the same may be tinned with solder to prevent exposing the core to atmospheric conditions. The portion of the wire jacket that is in actual engagement with the contact stud, or that actually forms an electric contact making surface may be coated with silver to increase the conductivity at the contact making points or lines. This may be done by any of the processes known. in the art.

The wires may be bent to any shape required for the blade member. In a simple switch the blade maycomprise two wires adapted to embrace the switch studs, which wires are drawn together intermediate the ends and spread apart by the contact stud or studs, the arrangement being such that the natural resiliency of the wire will maintain the same in firm pressure engagement with the studs. Where current carrying capacity in excess of that of the two wires is required a larger number of wires may be used. The wires may be bent into various shapes, such as hairpin shape, by way of example, and nested together to form the blade member. In other cases an entire blade may be formed from a single wire bent back andv forth to form a number of conducting paths between the contact studs of the switch.

It is an object of the present invention to pro-, vide a switch blade of the above mentioned character wherein each individual conductor makes contact with one or both switch studs, and the pressure between each conductor and the stud is predetermined, and is applied in such a manner that neither wear nor change in temperature will have any appreciable effect on the pressure. Furthermore, the accidental displacement of any single conductor can have no effect on modifying the contact pressures of the remaining conductors.

It is another object of the present invention to provide an arrangement wherein each switch blade comprises a plurality of conductors which come into engagement with the contact stud successively during the switch closing operation and wherein the respective conductors of the blade are flexed slightly in progressive sequence to give a definite pressure of each conductor against the stud. Because of the progressive flexing, single pole switches may be assembled and put directly into service without requiring adjustments to obtain proper pressures between the contacting surfaces. Because of the progressive sequence of flexing of the parts or wires of a switch blade the amount of force required to push'a blade into proper engagement with its contact stud is substantially reduced. 7

It is a still further object of the present invention to provide an improved holding means for wires assembled to form a switch blade of the above mentioned character. The holding means may be constructed to maintain the wires in engagement with the contact stud about which they pivot and prevent retraction of the wires from the stud when the switch is open, and to maintain the individual wires in proper pressure engagement with both switch contact studs bridged by the wires when the switch is closed.

It is a still further object of the present invention to provide a tilting insulator type switch with :a switch blade comprising a plurality of wires wherein the arrangement is such that the blade moves substantially parallel to itself throughout the entire switch opening and switch closing operation. Thus if the switch is mounted with the blade in a horizontal position, the-blade is maintained horizontal as it moves from the switch closed to the switch opened position, and vice versa. This permits the mounting of suitable sleet hoods over the entire blade structure in a simple manner if the switch is mounted outdoors. Likewise, this construction permits the mounting of a switch of thistype in a compartment of a metal-clad switchgear, for instance of the type shown in my patentapplication Serial No. 160,519, without requiring an excessively large compartment. It is a further object of this invention to provide such a rocking insulator type of switch whereinthe blade itself is so shaped as to produce the above mentioned type of motion. It isa still further object of the present invention to provide a switch of this type with a wire type blade wherein the blade itself is so shaped as to produce the above mentioned type of motion. It is a still further objectof the present invention to provide aswitch of this type with a wire type blade wherein the blade is so constructed that afterthe switch has moved a short distance in its switch opening operation the pressure between the-wire blades and contact studs will be substantially reduced, thus reducing the force required for switch opening operation. Conversely during the switch closing operation there will be substantially no pressure between the blade and the studs until the switch has moved almost to its fullyclosed position, when the blade fully grips both studs under pressure. This gripping action is effected by bringing. about a resilientspreading of the wires constituting the blade. The wires may thus act as a shock absorber for reducing the momentum of the movable parts immediatelyv preceding fullswitch closure, at the same time utilizing this momentum to bring the switch parts into proper pressure engagement.

It is a further object of this invention to provide a means for holding wire or similar contact making members of a switch in such a manner as to increase the creepage distance between the holding means and the live parts of the switch. Thisis particularly applicable to oil circuit breakers or the like, where compactness is essential.

The attainment of the above and further objects of the present invention will be apparent from: the following specification taken in conjunction with the accompanying drawings forming apart thereof.

In the drawings:

Figure l is a sectional view of a lever switch constructed in accordance with the teachings of the present invention, said view being taken along the line l-l of Figure. 2 and looking in the directionof the arrows; Figure 2 is a front view of the switch of Figure .1;

Figure 3 is a fragmentary diagrammatic view illustrating certain steps in the manner of forming the blade of the switch of Figure 1;

Figure 4 is a sectional view taken along the line 4-4 of Figure 3;

Figure 5 is an enlarged longitudinal sectional View through one of the contact making wires of the switch of Figure 1;

Figure 6 is a sectional view taken along the line 6-8 of Figure 5;

Figure 7 is a side elevation of a pole operated high voltage disconnecting switch embodying the present invention;

Figure Sis a plan view of the switch of Figure 7;

Figure 9 is a sectional view of the front end of the switch of Figure '7, side view section being taken along the line 9-9 of Figure 7;

Figure 10 is a sectional view taken along the line Iii-IE of Figure 8;

Figure 11 is an end view of the locking mechanism of Figure 19, said view being taken along the line I l-ll of Figure 10; v

Figure 12 is a sectional view taken along the line [22-12 of Figure '7;

Figure 13 is a View illustrating the manner of fabrication-of one wire switch blade of the switch of Figure 7; v

Figure 14 is an elevational view of another switch embodying the present invention;

Figure 15 is an end View of the switch of Figure 14 Figure 16 is a fragmentary sectional View taken alongthe'line Iii-l6 of Figure 14;

Figure .17 is an enlarged fragmentary View of one of the wire clamping means of the switch of Figure 14,- said view being taken along the line I'l-l! of Figure 16;

Figure 18 is a side elevation of another switch embodying'the present invention;

Figure .19 is a sectional view taken along the line l9-l9 of Figure 18;

Figure 20 is a front view of the switch of Figure 18;

Figure 21 is a sectional view taken along the line 2l-2l of Figure 18;

Figure 22 illustrates a detail for clamping one of the wires of the switch of Figure 18, said view being taken along the line 22-22 of Figure 21;

Figure 23,is a side elevationalview of a switch similar to that of Figure 18 but of higher current carrying capacity;

Figure 24 is a fragmentary sectional view taken along the line 24-24 of Figure 23;

Figure 25 is a View of a lever switch similar to that of Figure 1, and illustrating a different form of wire contact and a difi'erent means for pivoting the blade;

Figures 26, 27, 28 and 29 are views illustrating still other forms of bent wires for forming a switch blade for a lever switch;

Figure 30 is'an end view of the blade of Figure 29;

Figures 31 and.v 32 are, respectively, plan and elevational views of the switch blade of another form of pole operated high voltage disconnecting switch similar to that of Figures 7 and 14, with the blade trussed in two directions;

Figure 33 is a plan view of still another form of switch blade for a high voltage disconnecting switch;

Figure 34 is a sectional View taken along the line 34-34of Figur 33;

. Figures 35 and 36 are, respectively, front and side views of still another lever switchembodying the present invention;

Figures 37 and 38 are, respectively, front and side ,views of still another lever switch embodying the principles of the present invention;

Figures 39 and 40 are, respectively, plan and elevational views of the contactmaking end of still another switch blade embodying the prin- I ciple of the present invention;

Figures 41 and 42 are, respectively, plan and elevational views illustrating the present invention as applied to a rocking insulator type of disconnecting switch;

Figure 43 is a view illustrating the switch of Figure 42 in its open position;

Figure 44 is a fragmentary sectional view taken along the line 44-44 of Figure 42;

Figure 45 is ,a longitudinal sectional view through another type of disconnected. switch embodying the present invention; I I

Figure 46 is a transverse sectional view taken along the line 46-46 of Figure 45;

Figure 47 is a fragmentary sectional view taken along the line 41-41 of Figure 45;

Figure 48 is a sectional view taken along the line 48-48 of Figure 49 and illustrating the present invention as applied to th contact making means of a circuit breaker; I

Figure 49 is an elevational view of the circuit breaker contact breaking means of Figure 48;

Figure 50 is a sectional view taken along the line 50--50 of Figure 48;

Figure 51 is a diagrammatic sectional view through a circuit breaker having a contact making mechanism such as is shown in I Figures 48-50;

Figure 52 is a front elevational view of another form of circuit breaker contact making means embodying the present invention;

Figure 53 is a sectional view taken along the line 53.53 of Figure 52; I I

,Figure 54 is an end view of the contact mak ing mechanism of Figure 52;

Figures 55 and 56 illustrate alternate means of arranging the contact making wires for a circuit breaker of larger current carrying capacity than that of Figur 52; I,

Figure 57 is a plan view of the wires of another'form of contact making bridging bar of a circuit breaker; and

Figure 58 is a side elevational view of the wires of Figure '7. I I I I In the accompanying drawings similar reference numerals indicate similar parts throughout.

Reference may now be had more particularly to the lever switch shown in Figures 1 and 2. Th switch comprises the usual form of support or base I, of insulating material, on which are mounted contact studs 2 and 3 that are connected at the rear side of the base to line conductors 4 and 5, and are adapted to beinterconnected at the forward side of the baseby means of the switch blade of the present. invention. The contact studs 2 and 3 are preferably cylindricalor oval in cross section, thereby facilitating the making of point contact with the members of the switch blade, although it is to be understood that they may be of any other cross sectional shape whereby line contact instead of point contact is obtained. The stud 3 comprises a hinge stud for the switch blade, and for that purpose is provided with a hinge pin 1 that extends through the stud and projects outwardly at the opposite ends thereof. the hinge pin 1. l I

The blade comprises twosimilar groups of U- shaped or hairpin-shaped wires l0 and II adapted to embrace the opposite sides of the contact The blade pivots about studs; The groups of wires Ill and H are of similar construction. Each group comprises a plurality of long, narrow, U-shaped or hairpinshapedwires nestled together, with the two groups secured between the arms l2 and [3 of a U-shaped yoke or bracket of non-magnetic material. The arms [2 and i3 are joined by a bight portion M. The arms I2 and IS with the groups of wires l0 and H on the inner sides of the arms are secured together by means of a spacer block I6 and three bolts ll located about midway between the studs, which firmly clamp the groups of wires I0 and H between the arms 12 and I3. The hinge pin 1 extends through the nestled groups of hairpin wires I0 and II and through the arms I2 and I3 so that the 'pin con stitutes a hinge for the arms 12 and I3 thereby permitting turning but preventing longitudinal or lateral shifting of the arms on the pin 1. The lower edge of each of the arms [2 and I3 is bent inwardly to form a short ledge l9 against which the curved portion 20 of the outermost hairpinshaped wire of each group bears. It is thusap- .parent that each of the hairpin-shaped wires is extended through th space between the pin I and the ledge l9 whereby the groups of hairpin shaped wires are free to rotate about the pin 1 with the U-shaped bracket but cannot slide lengthwise of the arms l2 and I3 thereof. The bight portion IQ of the U-shaped bracket has an insulating handle 22 bolted or otherwise rigidly secured thereto but spaced from the bight portion M by a disc 23 of wood or other insulation.

The distance between the groups of wires l0 I and H, at the spacer I6, is somewhat less than the diameter of the studs 2 and 3. The ends of the wires are flexible so that they embrace'the studs, being flexed by the studs out of their normal position. The arms 12 and [3 of the U- shaped bracket are sufiiciently spaced from the ends of the wires to permit such flexing of the wires by the studs 2 and 3. It is therefore apparent that the individual wires maintain a pressure engagement with the studs 2 and 3 due to their own resiliency. In order that the wires may maintain a very high pressure against the studs the wires are preferably made, to include material of a high degree of elasticity whereby a large force is required to produce a small deflection. This is obtained, as will be pointed out as this description proceeds, by making each wire in the form of a tube of copper or other metal of high conductivity reenforced by an internal rod or tube of other material of greater elasticity than copper, such as alloy steel, 01' bronze or other non-magnetic material of high elasticity.

The forward end of the contact stud 2 is, preferably, of a conical shape whereby the same serves to guide the switch blade into proper position during the switch closing operation. As the switch is being closed the wires 25, 26, 21, etc. engage the stud in succession, and are successively flexed outwardly thereby. By reason of the successive flexing action on the wires, instead of ,a simultaneous action on all of the wires the amount of forcerequired to efiect aswitch closing operation is materially reduced. I

The individual hairpin shaped wires constituting the group of wires II] or II are free of the arms l2 and 13 of the yoke except at the center, where they are clampedbetweenthe arms. By reason of this arrangement a high degree of fiex ibilityis' obtained at the contact making ends of the Wires or loops, each wire being independently flexible at each of the two studs.

In; order to maintain a low contact resistance between the wires and the studs the wires as well as the studs may have a plating of silver, or a silver compound in the form of a wide line at the place of engagement between the wires and the studs. The silver coating or plating may be applied in a manner well known in the art.

From the description above given, it is apparent that each individual conductor makes contact with both studs, and it is also apparent that the pressure between each conductor and each stud is predeterminable and is applied in such a manner that neither wear nor change in temperature will have any appreciable effect in changing its value. Furthermore, the switch may be assembled with a greater or lesser number of wires as determined by the required current carrying capacity of the switch, without appreciable alterations in the switch design. The spacin block l6 determines the spacing between the two blade members midway between the studs and thus determines the pressure of engagement with the studs. The width of the spacing block is such that as the blade members come down on the opposite sides of the contact stud 2 successive conductors, as they ride on the contact stud, are bowed out slightly, in a progressive sequence. The extent of bowing is predetermined by the spacer block to give the requisite pressure of each conductor against the stud. Because of this feature single pole switches of this construction can be put into service as soon as they are assembled, without first having to undergo adjustments to obtain proper pressures between the contacting surfaces. The force for opening or closing the switch is always applied to the blades approximately midway between the contact studs thereby affording resiliency of action. However, if desired, the actuating handle may be connected adjacent the stud 2, as would be desirable with switches having longer switch blades. Under such conditions two spacing blocks corresponding to the block it are used, each located adjacent to but spaced from one of the studs 2-3, and the plates l2 and I3 terminate adjacent the stud 2, separate plates being provided adjacent the stud 3. Such a construction is illustrated in the switch of Figures land 8 to which reference will presently be made.

Multipole lever switches are made by interconnecting two or more single pole switches with a cross bar of insulating material. By making the U-shaped member of each pole, to which the cross bar is attached, of sufficiently light material to permit a small amount of lateral flexure,

or by making a loose connection between each U-shaped member and its corresponding switch blade, or by a combination of both measures, each pole can, if desired, be floated to make it automatically self aligning with its corresponding contact stud.

Reference may now be had more particularly to Figures 3 and 4 wherein I show one method of making the wire assemblies I and H for the switch of Figures 1 and 2. For this purpose there is provided a plate or template 38 having a pair of pins 3l--32 secured thereto and projecting outwardly therefrom. The pins are threaded to receive nuts 3334 at their outer ends, and are adapted to support a cover plate 35. One end of a wire is placed at 36,;midway between the pins, and the wire is looped around the pin 32 and then back aroundthe pin- 3|, being wound continuously, and successively around the two pins,until the desired number of loops or turns have been obtained, in this ine stance three complete turns. The end of the wire is then clipped off at 31, so that the ends 36 and 3'! are both located on the same side of the longitudinal center line between the pins' 3l-32 and midway between the pins. Thereafter the plate is removed and the bent wire assembly is removed and out along the center line 38 to form two similar blade halves, one half constituting the wire assembly it] and the other half constituting the wire assembly I i.

In Figures 5 and 6 I have shown enlarged sectional views of the end of the wire for forming the switch blades. The wire consists of an outer tube or jacket of copper or other metal of high conductivity into which is inserted a wire M which may be of steel. On switches of high current carrying capacity it is preferable that the wire core 4! be of non-magnetic material. A non-magnetic steel alloy, such as, for

instance, stainless steel or manganese steel may be used. Also, the core 4| may be of bronze or other alloy having great strength and elasticity. The core 4| may comprise a solid rod inserted into the tube 40, or it may itself comprise a tube inserted into the tube 40. After the composite wire has been bent into shape the core 41 cannot be withdrawn from the jacket 4% and no special means need be provided for retaining the core in the jacket. If desired, and when the core is made of non-magnetic material, such as stainless steel or bronze, as mentioned above, the wire including the jacket 40 and the core 4| may be formed and drawn as one integral wire so that the jacket is welded to the core throughout the entire surfaces of contact between the jacket and the core.

By forming the composite wire in the manner above set forth it is possible with a jacket of a given cross sectional area to insert either a solid or a tubular core and thereby obtain a wire wherein the ratio of copper to steel, or the ratio of jacket to core, is of any desired value. In those instances where the core may be affected by weather conditions, or wherein the core is hol low, the ends of each wire of the switch may be sealed by means of a coating of solder or the like, indicated at 43. In the section illustrated in Figures 5 and 6 I have shown the end of a wire wherein there is a maximum ratio of steel to copper for a jacket of this size. If a lower ratio of steel to copper is desired, for the same cross sectional area of copper, the core is made tubular instead of solid.

Reference may now be had more particularly to the switch illustrated in Figures '7, 8, 9, 10 and 11. This switch comprises the usual grounded base 58 having stationary insulators 5l-52 mounted thereon which carry contact studs 53-54, each terminating in a line receiving lug 55. In this switch the contact stud 53 is of a circular cross section whereas the stud 54 is of an oval cross section, as is apparent from Figure 8. In this switch, as in the switch previously described, the blade also comprises two similar groups of wires, indicated at 5'! and 58. The group of wires 5'! is formed in substantially the manner illustrated in Figures 3 and 4, that is, by winding a wire of the type illustrated in Figures5 and 6 about two pins to form a continuous loop of several turns. In this instance, however, the ends of the wire 59 terminate at an end of the loop instead of at the center of the loop, as is illustrated in Figure 13. In Figu e h end of th e 9 t rmina e a e same end of the loop. They may, however, terminate at opposite ends if desired. The blade halves 51 and 58 are bent so that when assembled together they will form a truss, as illustrated in Figure 8. Adjacent their forward ends the blade halves 51-58 are secured together in definite spaced relationship by a spacer block 6| which is of slightly lesser width than the contact stud 53. Three bolts 62 and a like number of nuts, secure the forward ends of the switch blade sections 51-58 together on opposite sides of the spacer block 6|. Between the spacer block 6| and the free ends of the loops 51-58 the individual wire portions of the blade are freely flexible. A U-shaped clip or yoke 65 loosely embraces the free ends of the loops of wires 51 and 58, being bolted to the blade by the bolts 82. The ends of the wires are free to flex towards and away from the arms of the U-shaped clip 65. The clip is sufliciently wide to permit the. wires to be flexed outwardly by the contact stud 53 without limitation by the sides of the clip opposite the contact stud. A lock 61 forming also an eye for a switch operating pull rod is mounted at the forward end of the blade in a manner which will be set forth morefully as this description proceeds.

The opposite ends of the blades 51-58 are hinged to swing about a pin 18 that extends through the stud 54. For this purpose the ends of the blade portions 51-58 are secured together in spaced relationship by two strips 1I-12, three spacer tubes 13-13-13, short plate-like clips 14-14, and bolts 15,,that extend through the clips 14, the strips 1I-12 and the spacer tube 13," all as is illustrated more fully in Figure 12. The tubes 13 secure the wires of the blade portions 51-58 a distance apart slightly less than the width of the contact stud 54 whereby the stud flexes the free ends of the wire outwardly a small amount, and by that flexing produces the necessary high pressure between the wires and the stud. The clips 14 are hinged to the stud 54 by the pin 18 so that the clip may rotate about the pin but cannot move radially thereof. The ends of the clips 14-14 are bent inwardly, as indicated at 11 in Figure 8, and thus hold the wire blade against movement radially of the pin 18.

From the description thus far given it is apparent that the switch blade of Figures 7 and 8 may be swung about the pivot 10 to establish or disestablish electrical connections between the contact studs 53-54. As the blade approaches its switch closed position it may engage the outwardly flared ends of guiding tubes 18-18 which serve to guide the blade into engagement with the contact stud 53. The upper end of the contact stud 53 is conicallytapered so that if the apex. thereof comes between the blades it wil guide the blades into proper position. I

As the successive wires engage the contact stud 53 they are flexed outwardly, successively; since the diameter of the contact stud 53 is slightly greater than the normal distance between the ends of the switch blade members 51-58 when the switch is in its open position. Due to the successive flexing of the individual wires of each blade member, the forcerequired for the closing operation is substantially less than would berequired if each blade were flexed outwardly, as a unit.

In order to prevent the switch from being blown open by the magnetic forces produced during short circuiting conditions, a lock 81 is provided, which look is of a construction such as is illustrated more fully in Figures 9, 10 and 11, to which reference may now be had. The lock comprises twosimilar latch members 8| and 82 pivoted about a spacer 83 on a pivoted pin 84 that extends between the switch blade members and through the U-shaped clip 85. The blade mem bers have a limited amount of permissible flexing movement longitudinally of the axis of the pivoted pin 84 by means of short cylindrical blocks 85. The latch member 8| includes a horizontal portion 88 and a downwardly extending portion 89 which, together with the similar parts 88 and 88' of the latch member 82 form an eye for receiving the end of the switch pole stick for operating the switch. The parts 88 and 89 and the corresponding parts 88f and 89 are of a channel cross section. The parts 89-88 form a housing 90 for a spring 8| which is secured at one end to the part89 and at the other end to the part 89' and thus serves to drawthe latch parts about the pivot 84 into the position illustrated in Figure 10. In this position the latches 8 I-82 are in the extreme position to which they can be urged by the spring, said latches bearing against the front or bight portion 93 of the clipv 65. When the end of a switch stick is inserted into the eye formed by the arms of the latch and is pushed or pulled to force the end of the switch blade away from the stud 53, it first engages the horizontal portion 88 of the latch 8I and thus swings the latch clock- Wise about the pivot 84, thereby bringing the hook of the latch out of engagement with the base of a conical collar 94 secured on the stud 53, and moves the latch until it engages the portion 95 of the opposite latch member. Thereafter further clockwise swinging of the latch 8| about the pivot 84 is prevented. The collar 94 constitutes an anchor for the locking device, and during the switch closing operation acts as a switch stop. Continued movement of the switch stick thereupon forces the switch blade out of engagement with the contact stud 53. The latch 82 is provided only for the purpose of latching the switch in .its opposite extreme position if the switch is a double throw switch, that is, provided with a contact structure analogous to the contact 53, butlocated to be engaged by the blade when the blade is in a at its other end, as may be seen inFigure 8. This produces a truss effect, strengthening the switch blade against being swayed or twisted out of a Reference may now be had more particularly to the switch illustrated in Figures 14, 15, 16 and 1'1. In this switch, each of'the blade members is formed of a single length of wireof the kind illustrated in Figures 5 and 6, bent into a continuous loop similar to the construction illustrated in Figure 13, but differing therefrom, however, in that here the inner end of-each wire loop is curled to form almost a complete circle, indicated at IN, to form a bearing for the'blade. In this switch, the two-blade members 182 and I83 are pivoted about a pivot pin I84 that extends through a contact stud I85, said pin extending through the loops I8I of the blade members I02-I83. By this arrangementldispense with the plates 14-14 of Figure 8; The two-blade members are spaced apart by aspacer I88 which is of slightly lesser thickness than the thickness position of alignment with the contact studs 53- bridged by the blade.

of the stud I05, and are firmly clamped on CD1 site sides of the spacer I06 by clamps "rpm and four bolts I08. Since the spacer I05 is slightly thinner than the stud I05,it is apparent that the stud I05 will spread the ends or the two switch blade members, and that the blade members will thereby exert a pressure against the stud I05 by reason of this spreading action. The'amount of pressure exerted by the individual wire portions of the blades will be determined by the amount of spread of the wire portions and by the construction of the wires. By changing the ratio of the steel or bronze core to' the copper jacket, I may obtain any desired degree of resiliency or elasticity of the end of the blade.

The blade parts I02I03 engage a contact stud II and are secured together adjacent to, but spaced from the contact making end of the blades, by clamping means substantially similar to that adjacent the pivoted end of the blades, as illustrated in Figures ld'and 1'7. The'clamping means adjacent the contact making end of the blade differs from the other clamping means primarily in that at the spacer corresponding to the spacer I06 an eye III is formed therein for receiving the endof a switch-operating stick. The spacer between the blade members at the contact making end of the blade is of lesser thickness than the thickness of the contactstud I I0, so that the contact stud spreads the blade 'members I02.I03 somewhat, thereby producing the required degree of pressure of the. blades against the stud. The contact making edges of the wires of this blade may be plated with silver or other metal having ahigher conductivity than that of copper, which plating may also be applied to the engaged portions of the studs I05 and H0.

As may be seen from the cross section of Figure 16, the wires of the blades are arranged in four groups forming the corners of a rectangle. At the clamping means, the bolts I 08 hold the wires against relative movement in any direction. It is known that the magnetic forces produced as an accompaniment of the flow of alternating current tend to force the current outwardly from the center of the conductor. In a switch of the present construction, if the blade is considered as a conductor, it is to be noted that thecenterfof the blade is hollow, that is, there is a space II2 between the opposite groups of contacting paths of each blade member. By reason of this arrangement, the copper is'pl'aced at the corners of a rectanglewhere it is of maximum effect in carrying the current, as distinguished from a solid blade construction.

Reference may now be had more particularly to the switch illustrated in Figures 18 to 2i 'inclusive. This switch comprises an insulating base I20 to -which is suitably secured a pair of contact studs I2I and I22 that are adapted t'o be The contact studs "are of similar construction, each comprising a wide block having a V-shaped contact-making edge I2 3. The blade of this switch comprises a group ofwires of the construction illustrated in Figures -5 and 6,,secured to a bracket comprising nonmagnetic side plates I2 iI25 hinged about the pivot I26 on a standard I21 secured to the insulating base I20. The side plates i24 i25 have a pair of clamping plates I28-I29 extending'between them at their upper "ends, which plates form a V-shaped groove,'as may be seen in Figure 21, within which the individual wires I30'are clamped. Each wire l 3 0 has'a bulge l'3I therein (Fig. 22'), and the clamping plate I20 has a 'pro- 75 jecting portion that fits into the bulge ISI, whereas the plate I29 has a circular cavity into which the bulge I3I' of the wire fits. The clamping plates I28--I29 are firmly clamped between the side plates I'24I25 by means of bolts I33, which bolts also serve to clamp a U-shaped saddle I34 in place.

The contact stud I2 I carries two wire conductors I35 that suport a copper arcing stud I35 and a carbon arcing stud I31. The clamping member I29 carries a fiat resilient copper bar I38 that has a copper arcing stud I39 at. the ,end thereof, cooperatingwith the stud I35. The side rails or plates I24 and I25 support a pair of wires I40, of the construction illustrated in Figures 5 and 6, that are looped around the bight portion of the saddle I34, as indicated at MI, and carry a carbon contact stud I42 at their remote ends cooperating-with the contact stud I31. A copper braid or other fleiiible conductor I43 connects the stud I22 with the wire I 40, and through the side plates I24-I25 with the convductor I38 and wires I30. v To open the switch of Figures 18 to- 20 the side plates I24I'25 are caused to swing about the pivot I26 in a clockwise direction. Any standard mechanism for swinging the platesv may be provided. The wires I30 are thus separated from the studs I2II22. This, however, does not result in an interruption of the circuit because the arcing contacts I-3B-I39 and I3I I' i2 are still in engagement. Upon further switch opening movement, the studs I36i39 first open,'thus shunting the entire circuit to the carbon arcing contacts I3'I-I42. Upon further switch opening movement, the bight of the saddle I34 engages the loop I4'I of the wire It!) and forces the contact stud I42 out of engagement with "the stud I31, thus interrupting the circuit. By this arrangement, itis apparent that the arc is taken primarily at the carbon contacts I3I-I42 and secondarily at the arcing contacts 136-439.

The wires I30 and I40 are preferably of a construction such as was previously described, via: a copper jacket around a core of ordinary steel or non-magnetic stainless steel, bronze or the like, the core being separate from the jacket, or integrally united therewith, as desired. The contact-making edges of the wires I30 may be silver plated, if desired, as may also "the contactmaking edges of the studs I2 II 22.

; In'the switchof Figures 18 to 20 inclusive, each or the wires of-the blade I30 is held at its center and is free to flexfat its ends. The flexing of each wire is independent of the flexing of the others, and the flexing of the one end of a wire is independent of theflexi'ng of the opposite end.

By this arrangement the individual wires may each be adjusted so that each maintains a proper pressure at contacts I2'I and "I22.

The Ushaped edges of the contacts "I 2 I 'I 22 'permitengagem'ent with a wiping action.

In Figures 23 and 24 I have illustrated how a switch of a construction like that of Figures 18 to 20 may be made for a lar'ger current carrying capacity than is provided by the switch of Figures 18-20. I'nj'this arrangement, the contact studs IZI and I22'are each provided with a similar stud 'I2I" and I22 of the same shape, but

somewhat longer, than the corresponding studs I2I and I22. In addition to the set of wiresISil, in V-shaped formation, there is another set I33 of similar construction and similarly. clamped n place, which seto). wires-bridge the studs I2I'I2'2'. nv shapaspacr I 56 is interposed between the clamping plates I28 and I29, said spacing plate being adapted to fit over the projections I3I on the wires I30 and to fit into like projections on the wires I30. In other respects the switch of Figures 23 and 24 is identical with that of Figures 18-20, and is provided with arcing contacts like that at I36,I39 and I31I42 oi the switch in Figures 1820. The wires are of a similar construction previously described. Upon the initial switch opening operatiomthe wires I30 and I30 will both be moved out of engagement with the contact studs, leaving the arcing function to be performed as heretofore described.

In Figure 25 I have illustrated a lever switch a t similar to that of Figures 1 and 2 and differing therefrom primarily in that here the arms I2 and I3 of the U-shaped holding bracket retain the wires against longitudinal movement in, a somewhat different manner. Here the inturned fiang-esIII of the arms I2 and I3 of the switch of Figures 1 and 2 are omitted. Instead, each of the wires of the blade is rovided with dents or protuberances I5I so that the bolts I1 that secureythe arms I2-I3 and the wire blades together fit into the protuberances at the outermost one of the nested wires. By this arrangement, longitudinal movement of the nested set of hairpin wires is prevented. In other respects, this switch is identical with the switch of Figures 1 and 2, and a further description at. this time is deemed unnecessary.

.Instead of providing the. wires of the switch blade with the dents or protuberances I5I, the individual wires may be curved to provide a loop 153 (Fig. 26) for receiving the pin 1 of the contact stud. The other wires have loops I54 exceeding 130 degrees, each extending around the loop of the next inner wire. The loop I53 through which the pin I extends, together with the loops I54 prevent longitudinal movement of the blade in the same manner as do the inturned flange I9Eof the switch of Figures 1 and 2.

In Figure 27 I have illustrated still another manner of holding the switch blade members against longitudinal movement. This is accomplished by bending the inner wire I55 to provide a-loop I56 similar to theiloop I53 for receivin the pin 1, and providing the inner-hairpinwire I55 with an additional loop I51 for receiving one of the bolts I1 that clamp the arms I2I3 toether. wire I55 will be held against longitudinal movement@ The succeeding hairpin loop wires I58 are bent to provide an enlarged portion I59 embracing loops I56-I51, whereby the succeeding By this arrangement the inner hairpin hairpin wires .158. are alsoheld against longitudinalmovement. The switch blade such as is illustratedin Figure 27 may be assembled in a switch such as is illustrated in Figures land 2, or Figure 25, whereby the inturned'flanges I9 of the arms I2--I3 of Figure 1 may be omitted.

In Figure 28 I show still another arrangement whereby the pin 1 and the bolts I1 may lock the switch blade against longitudinal movement without resorting to the inturned flange I9, 111 a lever, switch suchas is shown in Figures 1 and 2,;or Figure 25. In thistconstruction each wire has a dent I 5I as in the wires of theblazde of Figure 25, and the innermost ,wire I50 has, in addition, a loop I53 as inthe blade of Figure 26. Two. switch blades such as are shown in Figure ;28 are mounted in a switch such as shown in Figures; land 2, whereby the inturned flanges I9 I9may be omitted, w i

In Figures 29 and 30 there is shown an arrangement whereby two hairpin shaped wires are nested together, each of the hair-pin wires being provided with dent portions I3I corresponding to the portions I3I of the wire illustrated in Figure 22. This type of switch blade may be clamped in place by clamping means such as illustrated in Figures 1 and 2. I

In Figures 31 and 32 I have illustrated a wire switch blade for a switch of the type shown inFigure 8, but diifering therefrom primarily in that here the wires are trussed in two directions. The switch blade comprises two similar parts 51 and 58 mounted in the same manner as the switch of Figures '1 and 8. The outer wire of each blade is bowed outwardly as indicatedat I10 and HI. For this purpose there is provided an interme diate clamping member I12 which includes a pair of, plates I13 and I14 on opposite sides of each blade part, and suitable spacers I15 between the blades. Bolts extend through the spacers and secure the plates and the blades together. The plates I13 or I14 may have, as an integral part thereof, a spacing block that fits between the wire I10 and the wire I15, and a similar block that fits between the wire HI and I11, the said blocks serving to maintain the wires I10 and HI spread apart. This trussed type of construction is desirable for blades of great'length, since this blade is of considerable strength against bending in any direction. In other respects this switch is of a construction such as is illustrated in Figures 7 and 8 and therefore a further description thereof is believed to be unnecessary.

, In Figures 33 and 34 I illustrate another type of switch blade. This construction comprises four similar wires I80, I8I, I82, I83 threaded at their outer ends and secured 'to a rectangular supporting plate I84, by nuts I85, the wires extending through openings in each corner of the plate I84. The wires taper toward one another from the end I84 to the contact-making end I88 where the four wires are secured together in spaced relationship by means of a spacing block I81, clamping plates I38, and bolts I89. The four ends I 50 of the wires I I83 are adapted to embrace a contact stud or to move between the jaws of a contact stud, and are sufficiently fiexible at their ends outwardly of the clamping spacer I81 to permit flexing of the same by the contact stud, whereby the contact-making ends I90 of the wires exert a requisite amount of pressure upon the Contact stud. .Proper alignment of the four wires I80-I83 may be obtained by adjustment of the nuts I that thread over the ends of the wires. Suitable flexible braided .or other copper wire I92 is clamped or other-wise secured to the respective wires Hill-I83 to establish good electrical) connections with the blade. The supporting plate I84 is mounted for switch operating movement in any desired man- ,ner, as for a swinging movement or a combination. rectilinear and swinging movement, as is well known in the switch art. Because of the greater spacing of the ends of the wires at the plate I84 than at their contact-making end, this blade constitutes a truss of great strength against bending in any direction.

In Figures 35 and 36 there is shown still another type of switch embodying the principles of the present invention. This switch comprises one continuous length of Wire bent to form a contact-making length 20I which is bent around an insulating or insulated stationary circular support 202, as indicated, at. 203, then bent to extend along the support at 204, then again around the support 202 as .indicated at 205, and then bent to form another length. of wire 206 parallel to the length 20!. The two lengths ZEN-2'66 swing about the support 262 into and out of engagement with switch studs 201 and 208. Suitable clamping means 209 is provided for securing the wires 20l--266 together midway between the studs 201-208 and spaced apart a distance slightly less than the diameter of the studs 201 208. When the blade is moved into its switchclosed position the wires are spread apart slightly by the studs, wherebi the wires exert the requisite pressure against the studs. Suitable operating means may be secured to the clam ing means 209, .As shown this comprises a bar 2!! extending through a loop or eye 212 in the spa-oer plate ofthe clamping means. The wire or tube constituting this switch blade may be of the materials heretofore mentioned, comprising a copper jacket reenforced by a solid strengthening core of metal material having a higher elasticity than copper.

In Figures 3'7 and 38 there is shown still an other type of wire switch blade construction embodying the present invention. In this construction the blade comprises two similar blade members indicated at M5 and 216 pivoted on opposite sides of the contact stud 2|1 by means of a pin 218 that extends through the stud. The pin 218 extends'through a loop in the wires similar to the loop I53 of Figure 26. The two blades are secured together in properly spacedfrelationship by a clamping member 226 including a blade spacer to which an operatingeye 221'! may be secured. The switch blades are movable into and out of embracingrelationship to the contact clip 222, which is wedge-shaped at its forwar'd end, as indicated at 223, to guide the blades, on opposite sides of the clip 222. As the blades move over the clip 222 they are somewhat spread. and

the parts 224 of the blades exert the requisite pressure against the stud 222. There is consid erable length. of wire between the contact-making end of the blade and the clamping member 220, whereby the natural resiliency of the wire is utilized. Each of the wires is of'a construction such as was previously described.

In Figures 39 and 40 I have shown the contact-making end of still another switch blade constructed in accordance with the present invention. This switch blade comprises two solid copper blades. 236 and 23! secured together in properly spaced relationship by means of a spacer 232, clamping plates 233, and bolts 234. The forward end of each blade 236-23! is slitted along the lines indicated at 235 by means of a series of saw-cuts that extend for anappreciable distance from the contact-making end of the blade. Each strip of copper between adjacent saw-cuts is'flexible independently of theothers. The forward or c'ontact making'ends of the respective strips are bent toward one anothenas indicated at 238, to constitute the contact-making .portion' of the blade. The blade is movable into and out of engagement with a contact-stud 239 in any desired manner. When the blade is in its switch open position, the distance between the opposite contact-making fingers 238 238 is less than the thickness of the stud 239. As the blade is moved over the stud, the contact fingers are spread, whereby each contact finger "exerts its pressure against the studindependently ofthe oth'er contact fingers. The contact making portions of the fingers, as well as of the stud, may be silver plated.

Reference may now be had more particularly to the switch illustrated in Figures 41, 42 and 143. This switch comprises a grounded channelshaped base 25! on which are mounted stationary insulators 252 and 253, and a rocking insulator 254, which rocks about a stationary pivot 255. The insulator 252 supports a line terminal 256 having a contact stud 251 adapted to be engaged by the switch blade in a manner to be presently set forth. The insulator 253 supports a terminal 258 having a contact stud 259 engaged by the switch blade in a manner presently-set forth.

The switch blade comprises two similar blade members 266--26! clamped together to embrace the contact stud 259, and pivoted at the end of the rocking insulator 254, as'will be more fully set forth as this description proceeds. The blade 260 comprises a number of loops of wire, in this instance five, nested together. Each loop includes upper and lower inclined contact-making portions 263264, a straight or horizontal portion 265, and a circular curved portion 266. The circular portion merges with the horizontal straight portion 265 along a smooth curve 261, and merges with. the inclined contact-making portion 264 along a smooth curve 263. The wires of the switch blade 266 are nested together, as

illustrated in Figure 42. Adjacent their forward end the blade members 260-26! are secured together, and in properly spaced relation with respect to the stud 251 by means of clamp members 210-210, a spacer 21! and bolts 212. The clamp members are pivoted to the cap ofthe insulator I54 about the pivotal center 213. The clamps 21.0 and spacer 21! secure the two switch blades a distance apart slightly less than the diameter of the stud 251.

The blade members 266-26.! embrace the stud 259 and are guided in place by means of an up'-' per pin 211 and 'a lower pin 218 extending through the stud. l "The, horizontal portions 265 of the blades are secured together in properly spaced relationship by means of clamps 286-480 on opposite sides of the blades, a spacer 28!,anci bolts262-283, It is to be noted that'the clamp 2301s at an angle to thejwire'slof the blade; This angle is so chosen that the length of wire of the innermost loop at 284, between the adjacent bolt 282 and the pin 211 is equal to the length of wire of theoutermost loop between the adjacent bolt 283 and the pin 21 8. By this arrangement the pressure exerted against the stud .259 by the outermost wire of the loop is the same as the pressure exerted against the stud by the inner-- '-mos'twire, as well as by the intermediate wires.

The radiusof curvature of the outermost loop at 266 is exactly equal to the radiusfrom the center 255 to the pivot point 213. The center 'of curvature is indicated' at 288. The arcs .256 of each of the inner loops of Wires are arcs 'of circles about the same center 288. This is for'a purpose'to be presentlyset forth.

When the insulator 2'54 is rocked about the center 255 in a clockwise direction to open the switch, it causes the blades 2602'6! to move to the right, as seen'in Figure 42. As the point/.213

rises from the base'25l, causing arise of the turning of the insulator 254 causes the point 213 to "follow a circular curve which now approaches the base 25 I. At the same time, the arcuate portion 266 rides downwardly on the pin 218 an equal distance, so that the portion 265 still remains horizontal. This result is obtained by making the radius of curvature from 288 to the curved portion 266 equal to the radius from 255 to 213, as previously stated, and locating the center 288 in such a position that the four points 218, 255, 213, and 288 constitute the corners of a parallelogram. The switch blade therefore moves always parallel to itself so that the part 265 always remains horizontal when the switch is2 mounted in the position illustrated in Figure 4 The contact-making ends of the blades, comprising the straight inclined wire portions 263- 264, are outwardly flared at their forward end, as may be seen from Figure 41, to guide the switch blade over the contact stud 251.. The respective inclined wire portions 263264 are flexed outwardly by the contact stud 251, since the diameter of the stud is greater than the width of the spacer 21 I. Due to this flexing, the respective wires exert a spring pressure against the contact stud when the switch is in its closed position. Likewise, the ends of the blades that are on opposite sides of the stud 259 exert a spring pressure against the stud 259. Current therefore flows from the stud 258, through the upper and lower parts of each blade, to the stud 251. The mean efiective length from the stud 259 to the stud 251 over the upper half of the loop is approximately the same as over the lower half of the loop.

As the switch moves to its switch open position, which is illustrated more fully in Figure 43, the blades slide on opposite sides of the stud 259. In order to ease the operation of the switch, it is desirable that the pressure of the blades against the stud 259 should be released after the blades have separated from the opposite stud 251. This isacccmplished by forming a slight indentation in each of the wires at its point of engagement with the stud 259, as is illustrated more fully in Figure 44. As may be seen from this figure, each of the wil'es projects inwardly towards the stud a small amount, as indicated at 290. This amount may be of the magnitude of the order of 5- of an inch. As the switch blade is operated towards its switch closed position, the Wires loosely embrace the stud 259 until the forward end of the blade engages the stud 251. At that time, the inward projections 290 engage the stud 258 and thereby exert their pressure against this stud. This acts as ashock absorber tending to reduce the impact of the moving parts against the stud 251 and consequent shock on the insulator 252. During the switch opening operation the reverse action takes place, the pressure of the blades against the stud 259 being released when the blades have moved sufficiently to cause the projections 290 to clear that stud.

1 Reference may now be had to the switch illus- .filedDecember 28, 1936,although it is to be understood that this switch may be used in other connections, wherever desired. The contact-making mechanism is mounted in a tube 301 of porcelain or other insulation. The tube extends through a hole in a metal. wall 302 of the switchgear and is bolted in place by a ring 303 cemented to the tube and bolted to the wall 302. At the forward end of the tube 301 there is cemented or otherwise secured a copper ring 305 having an integral closure 306 through which is threaded a switch stud 301, suitably secured in place. The forward end of the stud 301 is square for receiving conductors suitably clamped thereto, and is hollow to facilitate cooling. At the rear end of the tube 30l there is mounted a short tube 310, of copper or the like, which is cemented or otherwise secured within the porcelain tube 301. The tube 3 1 El has a lug 3H projecting therefrom for receiving line connections. The switch blade for establishing connections between the stud 301 and the tube or terminal 310 comprises a series of wires 312, in this instance sixteen in number, secured together in assembled relation at the center of the wires, with each wire being free of all the others at both ends, and for the entire length of the wire from the center. The wires are, preferably, composite wires of the type shown in Figures 5 and 6. Each wire has an inwardly bent por-tion'3l3 at the center thereof. The wires are assembled on the inside of a copper or other ring 314 that has an internal peripheral projection 3l5 that extends into the bent portions 3I3 of the Wires. Thereafter a pair of circular discs 3l6 and 311 are inserted into the tube formed by the sixteen wires and are clamped together by extending a bolt 318 through the discs 316 and 3",, and'then tightening a nut at the end of the bolt. When the discs 3 1 63 11 are drawn together by tightening of the nut, the wires are forced outwardly and rigidly clamped between the discsiand the ring 314. A clevis 320 is pivotally mounted on the end of the bolt, and has an insulating operating rod'32l secured thereto. By pulling or pushing on the rod 32l the blade which comprises the wire assembly may be moved longitudinally within the insulating tube 301.

Each of the wires has an inwardly bent protuberance 322 at its forward end, which engages the contact stud 301 forming a point of contact therewith. Each of the wires 3I2 is bent at its rear end into a hook formation and extends over the rear of the tube 3! 0, as indicated at 325. Each hook portion has an inwardly bent projection 326 that makestcontact with the outside of the tube 310. The tube 3l0 is preferably, although not necessarily, beveled at its rear end, as indicated at 321, to facilitate guiding of the contact making portion 326 over the outside of the tube when the switch bladeassembly is moved to its switch closed position. The inside diameters of the circles formed by the contact making points 322 and 326 of the respective wires are somewhat less than the outside diameter of the stud 301 and the ring or tube 310, respectively, so that the individual wires are flexed outwardly at the contact making edges. This causes the wires toexert suflicient pressure to maintain good electrical connections. The contact making points may be silver plated, if desired.

In Figure 45 I have shown the switch in'its closed position, and have also shown, in dotted lines, the position of the rear end of the blade when the switch is open. The operating rod 321 may extend through a hole in a metal wall 330 of the switchgear, and is pulled to its open position by any suitable mechanism, for instance,

such as is disclosed in my pending application,

one supported within a. tubular insulator, being particularly applicable to installations wherein there. is provided a grounded or other apertured barrier between the lines or. buses, the invention is not limited to such an arrangement. For instance, in my application Serial No. 160,519, filed AugustZB, 1937, I show a disconnecting switch wherein the contact studs .or equivalent terminals are mounted on spaced vertically extending insulators and wherein the switch. blade is movable horizontally into andout of its switch closed position. Obviously the switch blade illustrated in Figure. 45 is applicable to such a switch. In such a! switch the rings 365 and 3H) would be supported on parallel spaced vertically extending insulators and the wire assembly comprising the switch blade would be movable between those rings in exactly the same manner as is illustrated in Figure 45. When the switch is moved towards its open position andthe wires leave the contact stud" 331 then in such a switch there-is no insulatorcorresponding to the insulator 361 for guiding the blade in its horizontal movement. Under those circumstances, the ring 3H] is made of somewhat greater length so that this ring serves to maintain the wire switch blade assembly in horizontal position when the wires leave the cone tact stud 361. Th mode. of operation of such switch would be exactly the same as of the switch illustrated in Figure 45, since themajor difference would be as to the means used for supporting the rings 365 and 3H).

Reference may now be had to Figures 48 to 51 inclusive, showing the principles of the present invention as applied to a circuit breaker. The circuit breaker itself is indicated diagrammatically in Figure 51, and comprises a head 34!) to which is secured a depending tank 34] of metal, having the usual cylindrical insulating liner 342; Insulating bushings 343 and 344 extend through the head 340 into the tank, and end in switch terminals 345-346 that are adapted to be bridged by the contact-making mechanism to be presently described. The contact-making mechanism comprises a U-shaped bridging member 348 supported by two metal rods 349 that extend into the circuit breaker head, and are adapted to be moved downwardly to lower the bridging member and interrupt the circuit. When the bridging member moves downwardlyit draws two arcs, one at the contact 345 and the other at the contact 346. The contact .i liiis in an enclosed chamber 356 filled with oil and devoid of any gases or other readily compressible media. This chamber communicates through an outlet 35l in an insulating plate 352 with the part of r 356, through the opening 35! into the chamber 351, which is open at the top to the space below the top of the circuit breaker head. The oil thus set into'motion and flowing through the opening 35l tends to cool and blow out the are formed at contact 346, thus interrupting the circuit.

Reference may now be had to Figures 48 to 50 showing the switch blade construction. In these figures I have shown the invention as applied to a three-phase circuit breaker within a single tank. The three phases are indicated at A, Band C of Figure 48. Since the contact-making structure 348 is the same for each phase, a description for'one phase will be sufiicient. Each bridging member comprises two groups of U-shaped wires 363--36l, of the type illustrated in Figures 5 and 6, clamped on opposite sides of an insulating bar 362, but spaced from the bar by spacer plates 363. Suitable clamping plates 364 on opposite sides of the bridging members clamp the bridg-, ing members against the spacer plates 363 and firmly secure the same to the insulating bar 362. The arms of the outermost U-shaped wire of each bridging member are of a somewhat greater length than the remaining wires, as indicated at 366, to serve for arcing purposes. Uppenand lower transverse beams 36! and 363 firmly secure the three insulating bars of the three phases together. The two operating rods 349349 extend through the transverse beams 361-466 and clamp the beams together into firm gripping rela tionship to the insulating bars 362 by means of upper and lower clamping nuts'369, and suitable spacers 316. By this arrangement, the operating rods 346 not only support the beams 361- 368, but serve also to clamp them in rigid gripping relation to the insulating bars 362 that support the respective bridging members.

It is to be noted that bight portions 313 of the bridging members are spaced from the insulating bars 362. This arrangement is provided in order to increase the creepage distance between the operating rods 349 and the bridging members. As may be seen from Figures 48 and 50, the creepage distance from the rod 349 to the bridging member extends along the beam 361 or 368 to the insulating bar 362 and then along the insulating bar 362 to the spacer 363, and then along the spacer to the bridging member. This creepage distance affords adequate insulation between live parts and the metal rods 349 located between adjacent phases.

The wires constituting the bridging members 348 are of a construction such as was previously described, namely, a copper tube with an internal reinforcement of metal of higher elasticity than copper. The inner core maybe welded to the copper jacket throughout the area of contact between the two, or may be separate therefrom. V The wires constituting the bridging memher are individually flexed outwardly by the contacts 345--346, and by that flexing are caused to exert the necessary pressure against the contacts. It is to be noted that the lower end of each contact stud 346 is tapered. Thus as the Wires ride on the contact studs they are progressively flexed outwardly, thereby easing the closing operation by acting as a spring cushion against shock.

Reference may now be had to the switch illustrated in Figures 52, 53 and 54. In this circuit breaker, the contact-making wires are of exactly the same construction as in the circuit breaker of Figures 48-50. Fine support for the wires and the rest of the bridging members are different. In this instance the two groups of nested U-shaped wires of each phase are clamped in spaced relationship by tubular spacers 366, clamping plates 36|332 and bolts 363. The bight portions of the U-shaped bridging members are secured in spaced relationship at their center by blocks 384 that receive an insulating operating rod 385 between them, and rectangular clamping plates 386. In this construction the operating rod must be of insulation, and there is one operating rod for each phase of the circuit breaker. In other respects,

this circuit breaker may be the same as that previously described.

If the circuit breaker of Figures 52-54 is to be of larger current-carrying capacity than that allowed by the two sets of U-shaped wire assemblies 360--36|, two additional sets of U-shaped wire assemblies 390 and 3! of a construction the same as that of the assemblies 360 and 36l may be provided. This is illustrated in Figure 55. These wire assemblies are spaced from the assemblies 360-36l by short spacers 392, and rectangular plates 386, which correspond, respectively, to the spacers 382 and plates 386. The assemblies are secured together by bolts 383', which correspond to the bolts 383 of the circuit breaker previously described, except that they are longer. In this construction, the bridging member for each phase is slightly wider than in the circuit breaker previously described. The arm portions of the U-shaped bridging members 390 and 39l are somewhat longer than those of the bridging members 360 and 36!. The contact 346, which corresponds to the contact 346 of Figure 54, is somewhat wider and it includes two additional contact-making edges 393, and additional tapered surfaces 394 for guiding the bridging members 39039l in position. In this construction the arcing extension 366 on the outermost wire of the bridging assemblies 360 and 36| may be omitted and the corresponding arcing arrangement provided on the corresponding- U-shaped wire of the assemblies 390 and 3!. In other respects, this construction is the same as that previously described.

It is to be noted that the addition of the two wire assemblies 390--39| to the switch of Figure 52, necessarily increases the over-all height of the switch, since the contact point 393 is above the corresponding contact edge 395. If an increase in height is to be avoided, the increased capacity may be obtained by a greater increase in the widthoi the contact structure. This is illustrated in Figure 56, wherein the ,additional bridging members 390' and SM are of the same height as the bridging members 360 and 36L Here, however, the contact structure 391 must be of greater width than the contact 346' in order to permit the contacting edges 398 -398 to be located at the same horizontal level as are the contacting edges 395. The wire assembly 390 is secured between clamping plates 382 at the sides and central clamping plates 386 spaced from the corresponding plates on opposite sides of the assembly 36| by tubularspacers 380' and 393, respectively. bolts 383 and 383', but somewhat longer, secure the assembly together.

In Figures 57 and 58 I have illustrated still another form of bridging member for a circuit breaker. This bridging member comprises an assembly of wires 40C and an assembly of wires 402 adapted to be secured together at their center portion 403 in spaced relationship with an insulating operating rod extending through the center portions 403. The ends 406 of the contact-making wires are free of oneanother'and freely flexible, the contact-making wires being secured together only at their center portion 403. The contact-making ends 406 are adapted to be moved into and out of engagement with a con- The wires constituting this switch blade are of Bolts, corresponding to the a construction such as is illustrated in Figures 5 and 6 heretofore described.

In each of the wire switch blades or contact making parts of the switching structures herein described the Wires are of a construction such as is illustrated in Figures 5 and 6, namely, a copper jacket reenforced by a rod or tube of material having a higher elasticity than copper. The reenforcing filler may be ordinary steel, or low magnetic stainless steel or other alloys, or nonmagnetic material such as bronze or the like. In those switch blades where the copper itself has the necessary strength and elasticity the internal reenforcing core may be omitted entirely, using either solid or hollow tubular wires or rods. While the wires have been shown as of a circular cross section this is not an indispensable part of the invention, as square or other polygonal shapes may be used. In each of the constructions herein illustrated the individual wires are clamped together at an appreciable distance from the contact making portion of the wire, and each wire is individually flexible and may be bent mechanically independently of each of the others to adjust its normal position so that it will be flexed a suflicient amount by the switch contact stud to cause the wire to maintain the requisite pressure against the stud, regardless of the relative spacings of the wires by the clamping means. In each construction the arrangement is such that if any one of the wires is out of proper position it cannot affect the pressure adjustment of the other wires. This is true whether the misadjusted wire is too far from the contact stud so that it exerts an insufficient or no pressure against the stud, or whether the misadjusted wire is too close to the stud whereby it exerts an excessive pressure against the stud. Furthermore, in each of the switches herein illustrated the blade may be readily assembled from standard lengths of wire, and the parts will require no machining to bring the movable members into proper alignment with the stationary members. The wires are so arranged with respect to the contact studs, that the magnetic forces resulting from the current flow are in such directions as to force the individual wire into firmer pressure engagement with the studs, rather than out of pressure engagement with the studs. Also, in each of these constructions the contact making portions of the blade and of the stud may be silver plated to reduce the contact resistance, without requiring silver plating of the entire wire lengths. By reason of the wire arrangement the switch blades have a large exposed surface area thereby increasing the radiating surface and thus facilitating cooling of the blade.

In compliance with the requirements of the patent statutes I have here shown and described a few preferred embodiments of my invention. It is, however, to be understood that the invention is not limited to the precise constructions here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to'secure byLetters Patent is:

l. A switch blade comprising a plurality of U-shaped wires nested together with at least a portion of one of the U-shaped wires lying between the arms of another U-shaped wire, and means securing the nested wires in assembled relation. i

2. A switch blade comprising a plurality of wires in the form of long U-shaped loops nested together with at least a portion of one of the U-shaped wires lying between the arms of another 

